I have a Panasonic TV/VCR combo that started displaying a black rectangle over the center ~80% of the screen. The black rectangle disappears temporarily when the volume is adjusted or when the channel is adjusted, returning in a few seconds. When the black rectangle disappears the image is OK. When the rectangle is present, the outer edge of the image also looks OK. This is observed with both cable and VCR signals. There are no problems with sound and the OSD adjustments all respond normally.
Any ideas what this is about, and sugestions for fixing this?
Thanks in advance, AFZ Panasonic PV-M2058 November 1998 Serial K8AA26685